In general, shaving razors of the wet shave type include a cartridge or blade unit with at least one blade with a cutting edge which is moved across the surface of the skin being shaved by means of a handle to which the cartridge is attached. The cartridge may be mounted detachably on the handle to enable the cartridge to be replaced by a fresh cartridge when the blade sharpness has diminished to an unsatisfactory level, or it may be attached permanently to the handle with the intention that the entire razor be discarded when the blade or blades have become dulled (i.e., disposable razor). The connection of the cartridge to the handle provides a pivotal mounting of the cartridge with respect to the handle so that the cartridge angle adjusts to follow the contours of the surface being shaved. In such systems, the cartridge can be biased toward a rest position by the action of a spring-biased plunger (a cam follower) carried on the handle against a cam surface on the cartridge housing.
Razor cartridges usually include a guard which contacts the skin in front of the blade(s) and a cap for contacting the skin behind the blade(s) during shaving. The cap and guard aid in establishing the so-called “shaving geometry”, i.e., the parameters which determine the blade orientation and position relative to the skin during shaving, which in turn have a strong influence on the shaving performance and efficacy of the razor. The cap and the guard may aid in establishing the exposure of the blades. Exposure may be defined as the position of the cutting edge of a blade relative to a tangent line drawn from the skin contacting element (e.g., a blade) in front of the cutting edge to the skin contacting element behind the cutting edge (e.g., the cap). A cutting edge positioned above the tangent line would have a positive exposure and a cutting edge positioned below this line would have a negative exposure. A cutting edge that lies on the tangent line has a neutral exposure. Another shaving parameter that significantly effects shave performance is known as span. Span may be defined as the distance from the cutting edge to a skin contacting element immediately in front of the cutting edge (e.g., another blade or the guard). Another parameter that may influence shaving performance is the blade angle. The blade angle is the angle of the cutting edge relative to the tangent line (described above).